A first related art is disclosed in Japanese Unexamined Patent Publication JP-A 2000-140143. A fire extinguisher of the first related art includes an air cylinder which is filled with compressed air, and a liquid tank which is filled with a fire extinguishing liquid, the air cylinder and the liquid tank being communicated with each other. The fire extinguisher further includes a jet gun for spraying the fire extinguishing liquid in the form of mist. The jet gun is connected to the liquid tank by way of a spraying hose through which the fire extinguishing liquid is led by inner pressure of the liquid tank. The jet gun has an on-off valve and a spout nozzle, and is capable of spraying the led fire extinguishing liquid in the form of mist from the spout nozzle by switching the on-off valve to an open state. In the fire extinguisher, a breathing apparatus is further provided. In the fire extinguisher thus configured, compressed air of 5 MPa or more and 30 MPa or less fed to the air cylinder is led into the liquid tank, and the compressed air causes the fire extinguishing liquid to be delivered by pressure to the jet gun and be sprayed in the form of mist from the jet gun.
A second related art is disclosed in Japanese Unexamined Patent Publication JP-A 2003-190314. A two-fluid fire extinguisher of the second related art includes: an air cylinder which is filled with compressed air; a liquid supply source capable of supplying a pressurized liquid; a two-fluid nozzle for spraying in the form of mist a mixture of the compressed air and the pressurized liquid; an air hose for leading the compressed air to the two-fluid nozzle, which is connected to the air cylinder and the two-fluid nozzle; and a liquid hose for leading the pressurized liquid to the two-fluid nozzle. In the two-fluid fire extinguisher thus configured, the compressed air led from the air cylinder and the pressurized liquid led from the liquid supply source are mixed in the two-fluid nozzle and then sprayed in the form of mist.
In the fire extinguisher of the first related art, the compressed air of 5 MPa or more and 30 MPa or less is led from the air cylinder into the liquid tank, whereby water can be sprayed in the form of mist from the spout nozzle. Since the compressed air of 5 MPa or more and 30 MPa or less is led into the liquid tank, the liquid tank needs to have sufficient resistance against the pressure. In order to provide such resistance, the liquid tank needs to be thick-walled, which causes the liquid tank to have a larger weight, resulting in an increase in a weight of the fire extinguisher.
If the pressure of the compressed air is lowered to a level below the range disclosed in the first art in order to have the liquid tank thin-walled, the extinguishant will be sprayed in a decreased amount and therefore fail to be sprayed in dense mist, which failure makes it difficult to enhance fire-extinguishing efficiency. It is therefore difficult in the fire extinguisher of the first related art, to take advantage of the decrease in the pressure of the compressed air for obtaining a thinner-walled configuration.
In the two-fluid fire extinguisher of the second related art, the compressed air contained in the air cylinder and the liquid fed from the liquid supply source are mixed in the two-fluid nozzle to form misty water which is then sprayed to a to-be-extinguished object. By spraying the misty water as above, a fire on the to-be-extinguished object is extinguished. In the two-fluid fire extinguisher, the compressed air and the liquid are mixed to form the misty water, in which process a large amount of the compressed air is required. If an amount of the compressed air contained in the air cylinder is small, a length of spray time is short, which causes a difficulty in extinguishing fire sufficiently. It is therefore necessary to increase a capacity of the air cylinder in order to extend the length of spray time. Such an increase in the capacity of the air cylinder inevitably accompanies an increase in a weight thereof, with the result that the fire extinguisher becomes larger in weight.